Air cleaner



S. H. BEACH Feb. 10, 1953 AIR CLEANER Filed Feb. 7, 1951 2 SHEETS-QSHEET 1 IIIIIIIIIIIIIIIIIIII I Ihmentor Cittornegs S. H. BEACH AIR CLEANER Feb. 10, 1953 2 SHEETS-SHEET 2 Filed Feb. 7, 1951 l'mventor z wwflw (Ittomegs Patented Feb. 10, 1953 AIR CLEANER Silas Harold Beach, St. Paul, Minn, assignor to Donaldson Company, Inc., St. Paul, Minn, a

corporation of Delaware Application February 7, 1951, Serial No. 209,718

9 Claims.

Generally stated, my invention relates to improvements in air cleaners of the kind employing a body of free-flowing liquid, usually oil, to separate air-borne dust and similar foreign substance from a column of air, such cleaners being commonly used in connection with the air intake systems of internal combustion engines, compressors and analogous air-consuming devices, and being commonly referred to as oil-washed air cleaners or as wet air cleaners. In a more specific sense, it may be said that my invention relates to improvements in wet air cleaners of the general character disclosed and claimed in the Wilfred W. Lowther Patent No. 2,387,278 of October 23, 1945.

A particular object of the invention is the provision of an improved air cleaner of the general character described, whereby to prevent the carrying over of the cleaners oil or other liquid into the air intake system of an associated in ternal combustion engine 01' corresponding air consuming device, under certain abnormal conditions, when the normal air passageway leading upwardly from the bottom portion of the cleaner becomes partially or wholly plugged. This important objective will be elaborated upon and other objectives made apparent from the following specification, claims and appended drawings.

In the accompanying drawings, like characters indicate like parts throughout the several views.

Referring to the drawings:

Fig. l is a view in side elevation, with some parts broken away and some parts shown in axial section, of a commercial air cleaner embodying a preferred form of the invention;

Fig. 2 is a transverse sectional view on a reduced scale, taken on the line 2-2 of Fig. 1 and looking downwardly;

Fig. 3 is a greatly enlarged fragmentary sectional view corresponding to the lower sectioned portion of Fig. 1; and

Fig. 4 is a fragmentary transverse sectional view taken on the line 44 of Fig. 1.

In the drawings hereof, a preferred embodiment of the invention is shown as being incor porated in a commercial form of air cleaner of the variety disclosed and claimed in the said Lowther Patent- No. 2,387,278. The shell-like outer casing of the air cleaner illustrated is of generally cylindrical form and is indicated as an entirety by I. This outer casing I comprises an intermediate cylindrical section 2, a cup-like bottom section 3 closing the lower end of intermediate section 2, and a head section 4 forming an extension of and closing the upper end of I cylindrical section 2. The cup-like lower section 3 of the casing provides a liquid reservoir 5 in the bottom portion of the casing I and is detachably telescopically applied over the lower end of cylindrical section 2 to the extent permitted by a flange 6 and sealing gasket 1. The cuplike bottom section 3 of the casing may be detachably secured in the position illustrated by any suitable means, such for example as the split clamping band of the Lowther et al. Patent No. 2,273,210, not shown. The liquid reservoir 5 is adapted to be filled with a suitable cleaning liquid, such as ordinary engine oil, not shown, to a static level indicated by bead 8 on the intermediate portion of the cup-like bottom section 3. The head section 4 is shown as being a cast structure cored out to provide a head chamber 9. This head chamber 9 is in communication with the interior of the upper end of the casing I through a series of circumferentially-spaced clean air outlet passages I0 and is formed to provide an anchoring flange I I and a final clean air discharge passage |2, which latter is adapted to be connected to the air intake system of an internal combustion engine or other air-consuming device or apparatus.

Leading axially downwardly through the casing I and. into the-liquid reservoir 5 thereof is a central air intake conduit in the nature of a cylindrical tube I3. This central air intake conduit I3 is rigidly anchored in the cast head section II of the casing and has its lower discharge end disposed in spaced relation to the bottom of the casing section 3, but, nevertheless, below the normal static oil level in said section 3.

In the preferred arrangement illustrated, an upwardly opening inner oil cup IA is mounted fast on the bottom of the cup-like lower casing section 3 in concentric relation thereto and the center inlet conduit I3. The cylindrical sides of this inner oil cup I4 extends above the plane of the lower discharge end of air intake conduit l3 and to, or slightly above, the plane of the normal static oil level in the reservoir 5. The cylindrical Wall of this oil cup is of materially greater diameter than the air intake conduit I3 and of considerably less diameter than the cylindrical portion of the outer casing I.

concentrically disposed about the lower discharge end portion of the air intake conduit I3 is an annular battle wall structure, indicated as an entirety by I5, and which, as shown, comprises a tubular portion I6 having an integrallyformed radially outwardly and upwardly directed annular flange l1, and a detachably applied outwardly and upwardly extending annular flange 2| and each thereof is welded or otherwise rigidly secured to the discharge end portion of intake conduit 13 and is provided below the discharge end of said conduit with a wing nut 22. The circumferentially-slotted anchoring flanges 28 are integrally formed with an anchoring ring 23 rigidly secured to the lower end of tubular portion 56. The upwardly and outwardly directed annular baffle wall structure it comprising portions 16, [1, l8 and 19, together with the lower portion of the air intake conduit l3, define a quiescent liquid-collecting zone or area 24 in the chamber space immediately overlying said bailie structure and further define a generally annular liquid re turn passage 25 leading downwardly from said quiescent liquid-collecting zone into the liquid reservoir 5 at a place immediately adjacent the discharge end of the intake conduit 13. The outer peripheral edges of the baille wall flanges l7 and 18 define the inner margin of an annular air flow passage 28, which is spanned by a generally conical annular screen structure 2'1 through which all air passes under normal operating conditions.

As shown, the screen structure 27 comprises a superposed plurality of conical annular woven wire screens 28, each reinforced at its inner edge u with a cross-sectionally U-shaped reinforcing ring 29 and at its outer peripheral edge with a similar reinforcing rin 32 The inner marginal edges of the several screens 28 of the screen element 2'! are detachably clamped between flanges I1 and I8 of the baffle structure it by means of a circumferentially-spaced plurality of wingheaded clamping bolts 3|. The outer marginal edges of the several screens of the screen element 21 are similarly clamped between upper and lower annular clamping flanges 32 and 33, respectively, the former of which is integrally formed with flange i8 and connected thereto by circumierentially-spaced spokes 34 and the latter of which is integrally formed with flange i1 and is connected thereto by circumferentiallyspaced spokes 35. A skirt-like annular splash bafile 36 is rigidly and permanently anchored to the clamping flange 33 and freely receives the upper end of the inner oil cup M to provide therebetween an annular oil flow passage 37. In order to insure equalization of pressure on opposite sides of the splash guard 35, the said baille is provided with circumierentially-spaced apertures 38 adjacent its upper end but below the screen element 21.

It should now be evident that when the liquid reservoir-forming bottom section 3 of the casing I is removed, that the entire bafile element [5 and screen structure 27 may be removed as a unit through the then-open bottom of the cleaner after first loosening wing nuts 22 and rotating the said unit to disengage the slotted anchoring flanges 20 from the bolts 2|. Also, it should further be evident that when the baffle structure and v screen structure 21 are thus removed as a unit, that the entire unit comprising bafile structure l5 and screen structure 2'! can be disassembled for cleaning by merely unscrewing the clamping bolts 3|.

The annular space within the casing l above the annular baflle wall structure 15 and screen structure 21 provides an expansion chamber 39; the aforesaid quiescent liquid-collecting zone being in the lower radially inner portion of this expansion chamber. Preferably, and in accordance with conventional practice, this expansion chamber 39 is provided with a filter element which, preferably and as illustrated, is of the loose-pack variety comprising a superposed plurality of corrugated annular woven wire screen element All, which may be assumed to be of the kind disclosed in the Schulz Patent No. 2,011,303 of August 13, 1935. This stack of screen elements 40 is securely held in position by retaining flanges 4| and 42 respectively carried by the intake conduit l3 and cylindrical wall section 2 of the casing. Preferably and as illustrated, there is a considerable space between the lowermost annular screen element 40 and the top of the baffle structure 15 and uppermost portion of screen structure 21.

In accordance with the invention and for the purpose of preventing the cleaners liquid from being carried entirely through and out of the cleaner under certain abnormal conditions, to be hereinafter fully explained, I provide an air diflusing baille structure 43 located in and spanning the annular expansion chamber space below the lowermost screen element 40 and through which all air traversing the cleaner must pass. Preferably, and as shown, this bafile structure 43 is spaced considerably above the annular bafile wall structure [5 and the screen structure 21 of air flow passage 26. In its preferred form illustrated, this bafiie structure 43 comprises an apertured annular bafiie plate 44 having a depending collar-like flange 35 at its inner marginal edge and a depending collar-acting flange 46 at its outer marginal edge, the former telescopically receiving the air intake conduit l3 and the latter being telescopically received Within the cylindrical wall of the outer casing. When the cleaner is completely assembled, the collaracting flange 46 of the bafile plate 44 is securely clamped between the screen element retaining flange 42 of the outer casing and the flange 32 of the screen structure 2?, and in this manner the entire air diffusing baiile structure 43 is se curely but detachably anchored in position. For the sole purpose of preventing accidental downward displacement of the battle structure 43 when the bafiie wall structure !5 and screen structure 27 are removed, I preferably provide a split spring retaining ring 4'! which is in sliding frictional engagement with the exterior of the air intake conduit 13 and is normally seated against the underside of collar-acting flange 45 of baflle plate M. It should be understood that the liquidcollecting quiescent zone 24, which is created by and is located above, the baffle wall structure I5, extends upwardly into the chamber 39 to a level well above the apertured baflie plate 44.

The air diffusing baiile plate 44 is provided with a multiplicity of closely-spaced apertures 48 which, in the preferred embodiment of the invention illustrated, are closed to straight-through passage of air vertically of the cleaner and are each directed at an oblique angle to the vertical and generally toward the space in the expansion chamber 39 overlying the quiescent liquid-collecting zone 24, the bafile wall structure l5 and the liquid return passage 25. In the preferred embodiment of the invention illustrated, these obliquely directed apertures 48 are each elongated in a direction generally circumferential of the annular baffle plate 44 or, otherwise stated, in a direction perpendicular to a plane radial to the axis of the cleaner and intersecting the intermediate portion of each such aperture. The elongated apertures 48 could be longitudinally arcuate and laid out concentric to the axis of the cleaner, but for the purpose of simplifying the manufacture, approximately the same result has been accomplished by elongating the apertures on a straight line. In the preferred embodiment of the invention illustrated, there are a plurality of circumferentially-spaced series of radially spaced apertures 48. As will be seen, particularly by reference to Fig. 2, the elongated apertures of each radially-spaced series thereof are of progressively greater length from the inside toward the outside of the bafile plate 44. In the structure illustrated, each radially-spaced series of elongated apertures 48 was formed by first cutting a radially-spaced series of slots 49 (se Fig. 2) in the baflie plate 44 to provide therebetween intervening louvers 5B, which were then rotated on their transverse centers to open up and form the apertures 48. If the apertures 48 were thus formed in the plate disposed radially of the cleaner axis, the said apertures would be open to straight-through passage of air vertically of the cleaner. However, in connection with the structure illustrated, it is important to note that the bafile plate 44 is of generally conical shape and flares outwardly and upwardly at a sufficient angle to close the apertures 48 to such straight-through passage of air axially or vertically of the cleaner.

Preferably, but not essentially, the air diffusing bafiie structure 43 further comprises a woven Wire screen element 5| which preferably is of the corrugated variety disclosed and claimed in the aforesaid Lowther et a1. Patent No. 2,273,210.

This corrugated screen 5| is disposed against the underside of baflle plate 44 and is held in place by inturned portions 52 and 53 of annular collars 45 and 45 respectively.

Operation Under normal conditions, the operation of the cleaner will be as follows: Dust-bearing air will pass down the central air intake conduit l3 into the inner oil cup 14, where it will impinge upon the oil therein, reverse its direction around the discharge end of the intake conduit I3 and the lower end of concentrically-disposed bafiie tube lecting zone 24 overlying the baffle structure [5,

from which it will be returned to the oil cup I4 of reservoir 5 through the annular oil-return passage 25, due to the suction or low-pressure efiect produced adjacent the discharge end of passage by the high velocity of the air stream past the discharge end thereof. The air thus discharged from the air flow passage 26, together with the balance of the oil borne thereby, is then carried upwardly through the bafile wall structure 43 into the screen-equipped expansion chamber 39. Although the annular air column expands considerably intermediate screen element 21 and the diffusing baiile wall structure 43, the main and highest velocity air flow through the apertured bafile plate 44 will, nevertheless, be through that portion thereof overlying the screen element 2?, so that the air velocity through the radially innermost bafiie apertures 48 overlying the bafiie structure 15 will be relatively low. As the oilladen column moves upwardly through the screen-equipped expansion chamber 39, the oil therein will be separated therefrom andcollected in that portion of the relatively quiescent zone or area 24 of chamber 39 above baflie plate 44,

wherefrom it will flow downwardly through the radially inner apertures or passages 48 of bafiie plate 44 to that portion of the quiescent zone 24 underlying the baffie structure 43, and from thence downwardly through the annular oil return passage 25, wherefrom' the oil is returned to the air stream or column for recirculation in the manner indicated.

The very fact that the baiile apertures 48 are directed obliquely with respect to the vertical, each in a direction inclined inwardly and upwardly toward the axis of the cleaner, aids materially in separating oil from the air column within the screened chamber 39. This is, of course, due to the fact that the jet of air directed from each of the baffle apertures 48 rapidly changes its direction within the lower portion of screened chamber 39 and in doing so tends to expel the oil therefrom by centrifugal action in th direction of the intake tube l3. Of course, it is also important to continuously return the collected oil from the space above the apertured baffle plate 44 to the space below the baffle plate 44. For this reason, it is important that the innermost apertures 48 of baffle plate 44 be shielded by the baiile structure i5, so that the velocity of the air flow therethrough is sufficiently low to allow a downflow of oil therethrough. In this connection, it is also important that the baffle apertures be of sufiicient area so that the air velocity therethrough of each thereof is sufiiciently low to prevent a high degree of liquid atomization. The screen element 5| of bafile wall structure 43 does, of course, aid in the diffusing of the rapidly moving column of air, but the main function thereof is to further aid in removing oil from the upwardly moving column of air and to direct collected oil radially inwardly to the quiescent liquid-collecting zone 24. In practice, it ha been found that the air diffusing bafile structure 43 hereof, although primarily designed for the purpose of preventing carry-over of oil to the cleaners outlet under certain abnormal conditions, also increases the efficiency of the cleaner materially, even under normal operating conditions, while at the same time not increasing the overall restriction of the cleaner objectionably.

As previously indicated, it is important, particularly under normal operating conditions, to

tively high near the top thereof, but is sufficiently low near the bottom thereof to allow return of oil downwardly thereagainst.

Under the usual operating conditions, the majority of the foreign matter carried into the air cleaner is ordinary earthen dust, which is readily trapped upon contact with the oil other cleaning liquid and is deposited in the oil reservoir This ordinar'y earthen dust has little tendency to plug the screen element l-lowever, in some localities, and particularly at cer tain times of the year, the air passed through the cleaner contains, in addition to the usual earthen dust, a considerable volume of vegetable fibers that will not pass through the screens of element 21 and, hence, rapidly choke up and plug the same. Under such abnormal conditions, the restriction of the screen element 27 builds up very rapidly to a point where the pressure below the oil return passage 25 becomes greater than the pressure t creabove and results in an abnormal upward movement or" air upwai through the oil return passage 25. Gr" course, after this action once commences, the volume and velocity of air passing upwardly through the liquid return passage 25 progressively increases as the screen element becomes further plugged and restricted, until finally all of the air mov through the cleaner passes upwardly througl oil return passage 25. Under these abncl conditions, the air moves upwardly through the oil return passage 25 at exceedingly high velocity,

due to the relatively small, and highly restricted cross-sectional area of passage and discharges upwardly into the normally quiescent liquid-collecting zone overlying the balile structure and immediately adjacent the inlet conduit 53.

Before the advent of the balile structure at of the instant invention, the high velocity jet of air thus upwardly discharged into the oil-collecting portion of the cleaner above baffle structure produced abnormally high atomization of the an countered liquid and carried much of the same completely through the screened expansion chamber 39 and the cleaners final outlet passage to the intake system or the associated internal combustion engine or other air-consuming device.

It will, of course, be understood that this abnormal carry-over oi oil was highly objectionable, first, because it soon deprived the cleaner of its liquid-cleaning agent; and, secondly, because of the essentially dirty character of the oil or other liquidcleaning agent carried over into the intake system of the engine or other aircon suming device, which often produced disastrous results in the nature or" very rapid wear, due to abrasive action.

With the baille structure :33 of the instant in- .vention incorporated in an air cleaner oi the described, the rapidly moving column or (lischarged upwardly from the liquid return passage 25, under abnormal conditions described, is diffused, spread out and greatly reduced in velocity by the interposed bafi'le structure 43, so that the velocity through the screened chamber 59 is relatively low and relatively uniform throughout the entire cross-sectional area thereof, with the re suit that the oil carried thereby is readily removed therefrom during its passage through the screened chamber 39. In this connection, it is further important to note that the bazlie apertu es be directed obliquely to the vertical and in a direction inclined toward the axis or" the cleaner, since this causes the jet of air moving through each individual aperture 43 to rapidly change its direction and expel therefrom much of its air-borne due to the relatively even distribution of the air column resulting from the diffusing baiile structure is, the air velocity through the said screen chamber 35 will not ordinarily be suificient to carry the oil completely through the chamber into the cleaners outlet.

My invention has been thoroughly tested and found to be completely satisfactory for the accomplishment of the objectives set forth; and while I have shot-a n and clesc 'ibed a commercial embodiment of my novel device, it will be understood that the sam is capable of modification without departure from the spirit and scope of the invention as defined in the claims.

What'I claim is:

i. In a wet-t; -a air cleaner, structure defining a generally vertically disposed shell-like outer casing having a closed bottom providing a liquid reservoir, a chamber above the liquid reservoir,

an air intake conduit discharging into the reservoir-forming bottom portion of the casing, and an air outlet passage leading from the upper portlon said chamber; wall structure located below said chamber and denning a quiescent liquid col lecting zone in the lower portion of said chamber above the plane of the discharge end of said intake conduit and a liquid return passage from said zone to the reservoir at a place adjacent the discharge end of the intalre con-suit, one edge of said wall structure being spaced from the uter casing to define therewith an air passage from the liquid reservoir to said chamber; a screen spanning said air passage; and an apertured air diiiusing baffle spanning the lower portion of said chamber and spaced above said screen element and said wall structure and through which all air entering said chamber must pass, said aperturecl air diffusing serving under abnormal conclitions when the said screen becomes cl used to diiiuse and reduce the velocity of which then passes upwardly through liquid return passage at high velocity, thereby greatly reducing the tendency to carry liquid through chamber to the cleaners air outlet passage under such abnormal conditions, ap tured air difiusing baifie comprising a plate having a multiplicity of spaced louvered apertures therethrough,

2. In a wet-type air cleane structure defining a generally vertically disposed shell-like outer casing having a closed bottom providing a liquid reservoir, a chamber above the liquid reservoir, an air intake conduit discharging into the reservoir-forming bottom portion of the casing, and an air outlet passage leading ruin the upper portion of said chamber; wall structure located below said chamber and defining a quiescent liquid collecting zone in the lower portion of said chamber above the plane of the discharge end of intake conduit and a liquid return passage from said zone to the reservoir at a place adjacent the discharge end or the intake conduit, one edge of said wall structure being spaced from the outer casing to define therewith an air passage from the liquid reservoir to said chamber; a screen spanning said air passage; and an apertured air diifusing baflle spanning the lower portion of said chamber and spaced above said screen element and said wall structure and through which all air enteringsaid chamber must pass, said apertured air diffusing baffle serving under abnormal conditions when the said screen becomes clogged to diffuse and reduce the velocity of air which then passes upwardly through said liquid return passage at high velocity, thereby greatly reducing the tendency to carry liquid through said chamber to the cleaners air outlet passage under such,

abnormal conditions, said air difiusing bafiie defining a multiplicity of air passages therethrough each of which is directed angularly upwardly and laterally toward the quiescent liquid-collecting zone of said chamber above the said liquid return passage and is substantially closed vertically of the cleaner.

3. In a wet-type air cleaner, structure defining a generally vertically disposed shell-like outer casing having a closed bottom providing a liquid reservoir, a chamber above the liquid reservoir, an air intake conduit discharging into the reservoir-forming bottom portion of the casing, and an air outlet passage leading from the upper portion of said chamber; wall structure located below said chamber and defining a quiescent liquid collecting zone in the lower portion of said chamber above the plane of the discharge end of said intake conduit and a liquid return passage from said zone to the reservoir at a place adjacent the discharge end of the intake conduit, one edge of said wall structure being spaced from the outer casing to define therewith an air passage from the liquid reservoir to said chamber; a screen spanning said air passage; and an apertured air diffusing bafile spanning the lower portion of said chamber and spaced above said screen element and said wall structure and through which all air entering said chamber must pass, said apertured air diffusing baiile serving under abnormal conditions when the said screen becomes clogged to diffuse and reduce, the velocity of air which then passes upwardly through said liquid return passage at high velocity, thereby greatly reducing the tendency to carry liquid through said chamber to the cleaners air outlet passage under such abnormal conditions, said air diffusing bafile comprising a plate having a multiplicity of spaced louvered passages therethrough, the louvers of said passages substantially closing said passages to straight-through passage of air vertically of said cleaner, and said louvered passages being each directed angularly with respect to the vertical and toward a vertical plane passing through said liquid return passage.

4. In a wet-type air cleaner, structure defining a generally vertically disposed shell-like outer casing having a closed bottom providing a liquid reservoir, a chamber above the liquid reservoir, an air intake conduit discharging into the reservoir-forming bottom portion of the casing, and an air outlet passage leading from the upper portion of said chamber; wall structure located below said chamber and defining a quiescent liquid collecting zone in the lower portion of said chamber above the plane of the discharge end of said intake conduit and a liquid return passage from said zone to the reservoir at a place adjacent the discharge end of the intake conduit, one edge of said wall structure being spaced from the outer casing to define therewith an air passage from the liquid reservoir to said chamber; a screen spanning said air passage; and an apertured air diffusing baffle spanning the lower portion of said chamber and spaced above said screen element and said wall structure and through which all air entering said chamber must pass, said apertured air diffusing baflie serving under abnormal conditions when the said screen becomes clogged to diffuse and reduce the velocity of air which then passes upwardly through said liquid return passage at high velocity, thereby greatly reducing the tendency to carry liquid through said chamber to the cleaners air outlet passage under such abnormal conditions, said baffle being inclined in a direction away from the quiescent liquid-collecting zone and the space overlying said liquidreturn passage therefrom, said baffie having a multiplicity of apertures therethrough each of which is directed at an angle that is oblique to the vertical and inclines toward the chamber space overlying the liquid-return passage, and said baffie apertures being substantially closed in a direction vertically of the cleaner.

5. In a wet type air cleaner, spaced generally cylindrical walls defining an outer casing with an air inlet passage leading downwardly into its lower portion and a concentrically-located chamber leading upwardly from the lower portion of the casing, a downwardly displaceable bottom section for the casing defining a liquid reservoir in the lower portion of the casing having its bottom spaced below the discharge end of the inlet passage and wherein air passing from the inlet passage to said air chamber reverses its direction around the discharge end of the inlet passage, an air outlet from the upper portion of the casing, a centrally apertured annular baffle wall disposed concentrically with respect to and adjacent the discharge end of the inlet passage and providing a relatively quiescent liquid-collecting zone thereabove, the lower marginal edge of the bafile wall structure being generally spaced from the marginal edge of a wall of the inlet passage to define therewith a generally annular liquid return passage from said quiescent liquid-collecting zone to the air stream at a place immediately adjacent to but posterior of said marginal edge of the inlet passage wall, an upper marginal portion of said generally annular baflie wall defining a generally circular side of an upwardly directed air passage from the liquid reservoir to said chamber, a filter element supported by said generally annular baifie wall and spanning said upwardly directed air passage, and an apertured air difiusing bafile spanning said upwardly directed air passage and spaced above said filter and said bafile wall structure, said apertured air diffusing baflie serving under abnormal conditions when said filter becomes clogged to diffuse and reduce the velocity of air which then passes upwardly through said liquid return passage at high velocity, thereby greatly reducing the tendency to carry liquid through said cleaner to the cleaners outlet passage under such abnormal conditions, said air diffusing bafile comprising a plate having a multiplicity of spaced louvered passages therethrough.

6. In a wet type air cleaner, spaced generally cylindrical walls defining an outer casing with an air inlet passage leading downwardly into its lower portion and a concentrically-located cham ber leading upwardly from the lower portion of the casing, a downwardly displaceable bottom section for the casing defining a liquid reservoir in the lower portion of the casing having its bottom spaced below the discharge end of the inlet passage and wherein air passing from the inlet passage to said air chamber reverses its direction around the discharge end of the inlet passage, an air outlet from the upper portion of the casing, a centrally apertured an ular bafile wall disposed concentrically with respect to and adjacent the discharge end of the inlet passage and providing a relatively quiescent liquid-collecting zone thereahove, the lower marginal edge of the baffle wall structure being generally spaced from the marginal edge of a wall of the inlet passage to define therewith a generally annular liquid return passage from said quiescent liquid-collecting zone to the air stream at a place immediately adjacent to but posterior of said marginal edge of the inlet passage wall, an upper marginal portion of said generally annular baffle wall defining a generally circular side of an upwardly directed air passage from the liquid reservoir to said chamber, a filter element supported by said generally annular bafile wall and spanning said upwardly directed air passage, and an apertured air diffusing baffie spanning said upwardly directed air passage and spaced above said filter and said ba'file wall structure, said apertured air diffusing bafi'le serving under abnormal conditions when said filter becomes clogged to diffuse and reduce the velocity of air which then passes upwardly through said liquid return passage at high velocity, thereby greatly reducing the tendency to carry liquid through said cleaner to the cleaners outlet passage under such abnormal conditions, said air diffusing baffie having a multiplicity of passages therethrough each of which is directed at an oblique angle to the vertical and is substantially closed vertically of the cleaner,

'7. In a wet type air cleaner, spaced generally cylindrical walls defining an outer casing with an air inlet passage leading downwardly into its lower portion and a concentrically-located chamber leading upwardly from the lower portion of the casing, a downwardly displaceable bottom section for the casing defining a liquid reservoir in the lower portion of the casing having its bottom spaced below the discharge end of the inlet passage and wherein air passing from the inlet passage to said air chamber reverses its direction around the discharge end of the inlet passage, an air outlet from the upper portion of the casing, a centrally apertured annular baiiie wall disposed concentrically with respect to and ad- ,iacent the discharge end of the inlet passage and providing a relatively quiescent liquid-collecting zone thereabove, the lower marginal edge of the baiiie wall structure being generally spaced from the marginal edge of a wall of the inlet passage to define therewith a generally annular liquid return passage from said quiescent liquid-collecting zone to the air stream at a place immediately adjacent to but posterior of said marginal edge of the inlet passage wall, an upper marginal portion of said generally annular baiiie wall defining a generally circular side of an upwardly directed air passage from th liquid reservoir to said chamber, a filter element sup-ported by said generally annular bafile wall and spanning said upwardly directed air passage, and an apertured air diffusing baiile spanning said upwardly directed air passage and spaced above said filter and said baffle wall structure, said aperture-d air difiusing baffle serving under abnormal conditions when said filter becomes clogged to diffuse and redrce the velocity of air which then passes upwardly through said liquid return passage at high velocity, thereby 12 greatly reducing the tendency to carry liquid through said cleaner to the cleaners outlet passage under such abnormal conditions, said air dif fusing bafile defining a multiplicity of passages therethrough that are directed angularly upwardly and laterally toward the space in said chamber overlying the said oil return passage and which are substantially closed vertically of the cleaner.

8. In a wet type air cleaner, spaced generally cylindrical walls defining an outer casing with an air inlet passage leading downwardly into its lower portion and a concentrically-located chamber leading upwardly from the lower portion of the casing, a downwardly displaceable bottom section for the casing defining a liquid reservoir in the lower portion of the casing having its bottom spaced below the discharge end of the inlet passage and wherein air passing from the inlet passage to said air chamber reverses its direction around the discharge end of the inlet passage, an air outlet from the upper portion of the easing, a centrally apertured annular baffle wall disposed concentrically with respect to and adjacent the discharge end of the inlet passage and providing a relatively quiescent liquid-collecting zone thereabove, the lower marginal edge of the bafile wall structure being generally spaced from the marginal edge of a wall of the inlet passage to define therewith a generally annular liquid return passage from said quiescent liquid-collecting zone to the air stream at a place immediately adjacent to but posterior of said marginal edge of the inlet passage wall, an upper marginal portion of said generally annular baffle wall defining a generally circular side of an upwardly directed air passage from the liquid reservoir to said chamber, a filter element supported by said generally annular baffie wall and spanning said upwardly directed air passage, and an apertured air diifusing baffle spanning said upwardly directed air passage and spaced above said filter and said baffle wall structure, said apertured air diffusing baffle serving under abnormal conditions when said filter becomes clogged to difiuse and reduce the velocity of air which then passes upwardly through said liquid return passage at high velocity, thereby greatly reducing the tendency to carry liquid through said cleaner to the cleaners outlet passage under such abnormal conditions, said air diiiusing battle comprising a plate having a multiplicity of spaced louvered passages therethrough, the louvers of said passages substantially closing said passages to straight-through passage of air vertically of the cleaner, and said louvered passages being directed angularly with respect to the vertical.

9. In a wet type air cleaner, spaced generally cylindrical walls defining an outer casing with an air inlet passage leading downwardly into its lower portion and a concentrically-located chamber leading upwardly from the lower portion of the casing, a downwardly displaceable bottom section for the casing defining a liquid reservoir in the lower portion of the casing having its bottom spaced below the discharge end of the inlet passage and wherein air passing from the inlet passage to said air chamber reverses its direction around the discharge end of the inlet passage, an air outlet from the upper portion of the casing, a centrally apertured annular baffle wall disposed concentrically with respect to and adjacent the discharge end of the inlet passage and providing a relatively quiescent liquid-collecting zone thereabove, the lower marginal edge of the bafile wall structure being generally spaced from the marginal edge of a wall of the inlet passage to define therewith a generally annular liquid return passage from said quiescent liquid-collecting zone to the air stream at a place immediately adjacent to but posterior of said marginal edge of the inlet passage Wall, an upper marginal portion of said generally annular bafile wall defining a generally circular side of an upwardly directed air passage from the liquid reservoir to said chamber, a filter element supported by said generally annular baille wall and spanning said upwardly directed air passage, and an apertured air diifusing bafile spanning said upwardly directed air passage and spaced above said filter and said bafile wall structure, said apertured air diffusing bafiie serving under abnormal conditions when said filter becomes clogged to diffuse and reduce the velocity of air which then passes upwardly through said liquid return passage at high velocity, thereby greatly reducing the tendency to carry liquid through said cleaner to the cleaners outlet passage under such abnormal conditions, said air diffusing bafile comprising a plate having a multiplicity of spaced louvered passages 14 therethrough, the louvers of said passages substantially closing said passages to straightthrough passage of air vertically'of the cleaner and said louvered passages being each directed angularly with respect to the vertical toward a vertical plane passing through said liquid return passage.

SILAS- HAROLD BEACH.

REFERENQES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 2,337,728 Acton Dec. 28, 1943 2,348,452 Christopher May 9, 1944 2,391,887 Donaldson et al. Jan. 1, 1945 2,507,897 Gavagnin May 16, 1950 FOREIGN PATENTS Number Country Date 120,304 Great Britain Nov. 7, 1918 120,345 Great Britain Nov. 7, 1918 354,215 Germany July 12, 1921 

